The objective of the work is to develop an implantable glucose sensor that potentially may permit the diabetic patient to attain better control over blood glucose, hopefully thereby reducing the severity of the disease. Previous research has demonstrated that an enzyme-membrane electrode, or enzyme electrode, in which glucose oxidase is immobilized as a membrane over a oxygen sensor is, in principle, feasible for this application. However, early efforts have shown that (1) certain critical limiting problems remain to be solved before this type of sensor can be realistically considered practical; and (2) that these problems must be addressed from a level of basic research. We, therefore, propose an integrated research program, fundamental in character, to: (1) design membranes containing immobilized glucose oxidase, in which the properties of substrate diffusion and reaction are well suited for sensor application; (2) investigate new methods of immobilization that may prolong the useful catalytic lifetime; (3) design and construct sensors; (4) estimate the potential analytical usefulness of such sensors by in vitro testing; and (5) document sensor biocompatibility. Our research effort is based on our previous success in developing enzyme-membranes that potentially have a useful catalytic lifetime at body temperatures. We will use a unique modeling approach together with a novel, rotated disc electrode device that we have developed for membrane study. Most importantly, our effect takes maximal advantage of a unique combination of research talent available at our institution.